The present invention relates to a voltage-regulator circuit for a system for recharging the battery of a motor vehicle which includes an electrical generator including an alternator with an armature winding and a field winding, and a rectifier, in which the output of the generator is connected to the battery by at least one connecting wire, the voltage-regulator circuit including:
a driver transistor whose collector-emitter path is in series with the field winding of the generator between the two poles of a source of a direct-current voltage, and PA0 a control circuit adapted to pilot the transistor in an on-off manner in response the value assumed by the voltage supplied by the generator in comparison with a reference voltage.
In voltage-regulator circuits of this type produced up to now, when the current supplied by the generator increases in operation, the voltage applied to the battery terminals tends to decrease. The voltage drop in the connecting wire or wires between the electrical generator and the battery contributes to this.
In order to reduce the variability of the voltage applied to the battery terminals with variations in the current supplied by the generator, it is necessary to provide a connecting wire between the positive pole of the battery and the voltage-regulator circuit (to supply that circuit with information relating to the instantaneous value of the voltage applied to the (battery). This is a disadvantage because it makes the wiring more complicated and also because, if the voltage-regulator circuit is in the form of an integrated circuit, it is necessary to provide a further terminal (pin).